The documentation says about the 'max' parameter that it is "the maximum
integer that can be returned". This is wrong. E.g.,
$x = random_bigint(min => 0, max => 1);
will never return 1. Several places in the code, the author has used
"int rand VALUE" apparently assuming that this can return VALUE, but it
can't. The expression "int rand VALUE" will only return values in the
range 0 .. VALUE - 1.
Besides, "int rand VALUE" will only return uniformly distributed
pseudorandom numbers if and only if VALUE is a power of two and no
larger than $Config{randbits}.
RT for rt.cpan.org